Rubber latex compositions heat-sensitized with polyalkoxy-1-alkanols



RUBBER LATEX COMPOSITIONS HEAT-SENSI- TIZED WITH POLYALKOXY-l-ALKANOLS George G. Stoner, Easton, Pa., Julian L. Azorlosa, Westbury, N. Y., and Charles P. Albus, Easton, Pa., assignors to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application September 9, 1955, Serial No. 533,527

12 Claims. (Cl. 26029.7)

This invention relates to natural rubber latex compositions which are heat-sensitized with polyalkoxy-l-alkanols.

In the rubber art, articles such as gloves, fountain pen sacks, bathing caps, meteorological balloons, sponge rubber, etc., have generally been produced by either a (1) straight dip, (2) coagulating dip, (3) gel-dipping, (4) molding, or (5) heat-sensitized latex process.

In the heat-sensitized latex process, a rubber latex is rendered heat-sensitive by the addition of inorganic vor organic compounds. An impermeable hot former mold is then dipped into the latex, held for a period of time toobtain a coagulate of the desired thickness, withdrawn from the latex, dried, washed in water to remove the watersoluble materials, dried, and cured. The heat-sensitized latices may be poured into molds which are subsequently heated to coagulate the latex. They may also be used for impregnating porous materials, such as paper, fcloth,'etc., squeezed to remove excess latex, and then coagulated by heat which also dries the impregnated article. 7

Many inorganic materials such as soluble bivalent and trivalent metal salts, mixture of zinc oxide and an ammonium salt of a strong acid, ammonium persulfate, sodium silicofluoride, and organic materials such as trimethyl cellulose, proteins of animal or vegetable origin and their degradation products, e. g., egg albumen, organic colloids such as gelatin; organic colloids such as celluloses, hemicelluloses, polysaccharides, viscose, etc., disubstituted guanidine, and nitroparafiins of 1 to 6 carbon atoms have been proposed as heat-sensitizers for rubber latex.

The foregoing heat-sensitizers have not come into commen use because of one or more defects. Latices containing additions of inorganic salts such as ammonium nitrate, calcium chloride, etc., tend to coagulate prematurely and to corrode storage drums and dipping pots. Proteins, gelatin, polysaccharides, and similar materials are subject to bacterial attack, and generally seem to do little more than concentrate or cream latex when used as heat-sensitizers. Nitroparaflins are ineffective alone and are used in conjunction with zinc oxide or oxides and hydroxides of elements of periods 2-6 of group IIjof the periodic table. In addition, these materials appear to be rather slow in their action as heat-sensitizers.

It is an object of this invention to provide heat-sensitized natural and synthetic rubber latex compositions which are stable on storage and non-corrosive to storage drums and dipping pots.

Another object is to provide heat-sensitized natural and synthetic rubber latex compositions which will readily coagulate around a form heated to temperatures of 30 to 130 0. within an extremely short period of time.

A further object is to provide a heat-sensitized natural and synthetic rubber latex composition which will yield relatively thick coagulates when contacted with a suitable hot form, either by immersion of the form in the latex for a very short period or by adding the composition to a hollow form or mold which is subsequently heated.

- Other objects and advantages will become more clearly apparent from the following description.

We have found that the foregoing objections to the prior art heat-sensitizers' are inlarge measure overcome through the use of water-soluble polyalkoxy-l-alkanols, or mixtures thereof, having the following general formula R ona-on onron omcnion where R and R represent a lower alkyl or l-alkoxyalkyl group, which may be the same or different, e. g. methyl, ethyl, propyl, butyl, etc., methoxyethyl, methoxypropyl, methoxybutyl, ethoxyethyl, ethoxypropyl, ethoxybutyl, propoxyethyl, propoxybutyl, butoxyethyl, butoxypropyl, etc., R" represents either hydrogen, a lower alkyl or a l-alkoxyalkyl of the same values as in R andR, and n is an integer ranging from 1 to 40. The polyalkoxy-l-alkanols are readily prepared in the conventional manner by the simultaneous saponification and hydrogenation of the corresponding polyalkoxy acetals as described in U. S.,P. 2,165,962. The polyalkoxy-lalkanols may also be readily'prepared by the simultaneous hydrolysis and reduction of the corresponding polyalkoxy acetals as described in U. S'. P. 2,618,663. In the latter process, the reaction is carried out in aqueous soluticn at a pH of 4.5 to 5.5 using a hydrolyzable metal salt of mineral or organic acids as-a catalyst injconjunction with Raney nickel catalyst and hydrogen at temperatures of to C. and 600 to 1000 p. s. i. hydrogen pressure. It is believed that the polyalkoxy acetal is first nydrm lyzed to the corresponding aldehyde and that this is then reduced to the corresponding alcohol in the following manner:

wherein R, R and n have the same value as above.

The polyalkoxy alcohols are also easily prepared as mixtures from the corresponding mixed polyalkoxy' acetals. For example, when 3 moles of methyl vinyl ether are reacted with one mole of methanol in the presence of boron trifluoride, the following mixed 'polyalkoxy acetals are formed:

3: 1 Polymethoxy acetals" Simultaneous hydrolysis and reduction of the mixed polyalkoxy' metals as shown above yields the following mixed polymethoxy alcohols:

L (ilCHaJr' 3 :-1 Polymethoxy' alcohols However, the latter formula represents only the average composition of the 3:]. polymethoxy alcohols formed by the hydrolysis and reduction of 3:1 polymethoxy acetals. It is to be noted that in practice they are obtained as a, mixture having the following approximate composition:

1. 35% 3-methoxy-l-butanol 1 GHPOH-OHPQHrOH OHa- I 2. 30% 3,5-dimethoxy- I-hexanol H- fCHr-QH CHPCHiOH L (hCHz-L 3. 20% 3',S,7'-triinethoxy-l-octanol H neon onr-onzon:

L 60ml.

4. 10% 3,5,7,9tetram'ethoxyl-decanol H CHPCIH CHPGHZOH L O CHaJL 5. 5% higher polymethoxy-l-alkanols L NT/H31 where n is greater than 4.

Although polyalkoxy acetals, individually or in admixture, yield good results as heatsensitizers', the polyalkoxyl-alkanols per se and mixtures thereof as employed in accordance with the present invention display the outstanding property of being more readily washed out by water from; the rubber composition after heat sensitization. Moreover, the said polyalkoxy-l-alk-anols are less soluble in the finished rubber compositions than the corresponding polyalkoxyacetals.

Individual members of the lowest homologous series of the polyalkoxy alcohols, polymethoxy alcohols, asdisclosed in U. S. P. 2,618,663 are as follows: 3-methoxy-lbutanol, 3,5 -dimethoxy-l-hexanol, '3 ,5,7-trimethoxy-1- octanol, 3,5,7,9-tetramethoxy-l-decanol, 3,5,7,9,11-pentamethoxy 1 dodecanol, 3,5,7,9,11,13 hexamethoxy ltetradecanol, 3,5,7,9,l1,13,l5 heptamethoxy 1 hexadecanol, 3 ,5,T,9,l 1,13,l5,l7-octamethoxy l-oetadecanol, and in general 3,5 (Zn-1)-polymethoxy-l-alkanols (where n= the number ofmolesiofmethyl vinyl ether used per mole of methanol to form the polymethoxy-l-alkanol) The number of methoxy groups present in the polyrnethoxy-l-alkanol will be n l. The number of carbon atoms in the polymethoxy-l-alkanol will be 2n. For instance, the polymethoxy-l-alkanol obtained from the simultaneous hydrolysis and reduction of 1,1 ,3, 5,7,9,l1,13,15-nonamethoxyhexadecane (isolated by fractional distillation of 4 the reaction product from 8 moles of methyl vinyl ether and one mole of methanol) has the structure:

and the name of this individual member is 3,5 19,11,- l3, lS-heptamethoxy-l-hexadecanol.

Higher homologs of the polymethoxy-l-alkanols, such as the polyethoxy-l-alkanols, polypropoxy-l-alkanols, etc., may be similarly defined. For example, the polyethoxyl alkanol obtained by the simultaneous hydrolysis and CHzCHsOH reduction of l,I,3,5,7,9-hexaethoxydecane (produced from 5 moles of ethyl vinyl ether and one mole of ethanol) has the structure:

CHzC HIGH and the" name of this homolog is 3,5,7,9-tetra(2-methoxyethoxyy-l-deeanol In like manner, the polyalkoxy-lalkanol produced from 2 molesof'n-octyl vinyl ether and onemole of n-octanol has the structure:

' 1 n-om-cn-omomon and the. name of this individual member of this series is 3- octyloxy-l-butanol.

. It is: to' be understood that the polyalkoxy-l-alkanols may be used: as the individual members starting with the lowest member of the homologous series, such as 3- methoxy-l-butanol for the 3,x-polymethoxy-l'elkanol series, as mixtures of 3,x-polyalkoxy-l-alkanols, or mixed 3,x.-polyalkoxy-l-alkanols may be topped or distilled so as to remove the lower-boiling 3,x-polyalkoxy-l-alkanols and. either the. low or high boiling fraction may be: used as heat sensitizersfor natural rubber latex. I

It is to: be further understoodthat we are not'limited to the polyalkoxy-I-alkanols listed above. The many individual' members and mixtures of water-soluble polyalkoxy-l a-lkanols which can be obtained when 1 to 40 moles ofmix'ed alkylvinyl ethers are reacted with one mole of an aceta'l or alkanol' and subsequently hydroylzed and. reduced to form polyalkoxy-lj-alkanols are equally useful as heat-sensitizers for natural rubber latex.

The polyalkoxy-Lalkanols are colorless 'to yellowcolored, fluid to fairly viscous liquids characterized by complete miscibility in water, aliphatic alcohols, ketones, esters, glycol etli'ers, etc. The water-solubility seems to decrease as the molecular weight of' the ether groups is increased. For example, the p olymethoxy-l-alkanol's appear to be somewhat more water-soluble than similar polybutoxy-or "high pol-yalkoxyd-a-lkanols. Inaddition, these materials have the rather novel property of being soluble in" coldflvvater and precipitating out of solution as the temperature is raised.

In carrying outthe invention, about 0:5 to 3% of 'a conventional stabilizing agent is first added to natural of any onezof the various .inorganic oriorganic acids.

The. filler, vulcanizing agents, color, and other compoundingiingredients are then added as a dispersion, and: lastly,

2' to 10%, and preferably 4 to 6% of polyalkoxy-alkanols are added. The latex is stirred or agitated by some suitable means as each addition is made to ensure complete solution or blending of each ingredient. After the polyalkoxy alkanols are added, stirring is continued for a few minutes.

The latex is now heat-sensitized and may be immediately used or allowed to stand for 12 to 24 hours. In some instances, it has been found that a slight ripening action, as evidenced by a slight or moderate decrease in the coagulation point of the heat-sensitized latex, may

occur when the latex is allowed to stand for a period of 12 to 24 hours. In either instance, it is advantageous to determine the coagulation point of the heat-sensitized latex after preparation and after storage for 12 to 24 hours. This will not only give the minimum temperature to which a form must be heated before it is inserted into the latex to obtain a coagulate but also indicate storage temperatures which will cause premature coagulation of the compounded latex. For example, we have found that natural rubber latices heat-sensitized by the addition of polyalkoxy-l-alkanols should be stored at temperatures at least to 15 C. below the coagulation point of the latex to prevent premature coagulation. However, for

best results, storage temperatures of to C. are

10 to 15 ml. of the heat-sensitized latex is poured into a 20 x ISO-mm. Pyrex test tube and a thermometer inserted. A 400-ml. dye beaker is half to three-fourths filled with cold water and placed on a hot plate. The test tube containing the latex and thermometer is then inserted into the water contained in the beaker and the hot plate turned on. The temperature of the latex is allowed to rise 2 to 5 C. per minute. time, the latex is intermittently stirred with the thermometer to prevent too great a temperature lag. The coagulation point is taken as the temperature at which all of the heat-sensitized latex coagulates into a solid mass of rubber. Coagulation of the latex into a solid mass of rubber appears to occur almost instantaneously at a given temperature and does not occur over a wide temperature range.

The natural rubber latex used may consist of purified, creamed, centrifuged, filtered, evaporated, or crude (plantation) latex. The natural rubber latex may be de-arn-moniated by blowing or any other suitable means to reduce the ammonia content before use. However, it is to be understood that we are not limited to the use of natural rubber latex. Synthetic rubber latices such as emulsions of polymerization products of 1,3-butadiene or mixtures of 1,3-butadiene with other polymerizable olefins or diolefins, alpha-methylene carboxylic acids and their esters, nitriles, amides, etc., and including polymerized 2-chloro-1,3-butadiene or like materials which when properly compounded and on the addition of polyalkoxy alkanols show a similar tendency to become heatsensitive.

The stabilizer is added in an amount sufficient to prevent coagulation of the latex when the pH is lowered to a value of about 7.5 or some higher desired value. For centrifuged natural rubber latex, we have found that generally additions of stabilizer ranging from about 0.5 to about 3%, and preferably from 0.5 to 1.5%, based on the total solids of the latex, is sufficient to stabilize the latex to additions of various strong acids, such as 1 N sulfuric, acetic, etc., acids. As the amount of stabilizer added is progressively increased over the minimum amount necessary to stabilize the latex to additions of acid, the coagulation point and stability of the heatsensitized latex will also increase until a point is reached when the latex is over-stablized and no longer able to coagulate around a hot mold or form dipped into the latex. For this reason, there is little orno advantage to be gained by adding any more stabilizer than the minimum amount necessary to stabilize the latex to additions of acid and help impart the necessary storage stability;

At the same Rubber latex stabilizers are numerous and have been described in the patent literature; For the purpose of the present invention, we prefer for the sake of expediency to employ those stabilizing agents disclosed in the third and fourth columns of U. S. P. 2,446,115 including the reaction product of ethylene oxide and oleyl alcohol in the mole ratio of 20:1. Alkylphenoxypolyoxyethylene-ethanols, condensation products of an alkylnaphthol with 8. moles of ethylene oxide as described in U. S. P. 1,970,578 and 2,213,477, may be used. All of these stabilizers are effective in preventing coagulation of natural rubber latex upon the addition of strong acids.

Various inorganic and organic acids may be used for lowering the pH of natural rubber latex. Examples of such acids are hydrochloric, nitric, phosphoric, sulfuric, acetic, formic, oxalic, tartaric and glycolic acid, etc. Various acid salts which are used in the art for lowering the pH of rubber latices may also be used. In addition, an aldehyde, such as formaldehyde, which is used to reduce the pH of rubber latices, such as natural rubber latex, may also be used. It is to be noted that as less acid is used the coagulation point and stability of the latex increases. For some applications this may be highly desirable. However, for the purpose of the present invention, especially when employing the polyalkoxy alkanols, the pH may be lowered from its original value to 9.0, 8.0, 7.5, or any intermediate value by the addition of either sulfuric acid, or any of the above-mentioned acids or acid salts. However, if the pH value of the latex is too high after the acid is added, no heat-sensitization will occur when the polyalkoxy alkanols are added.

The vulcaniz ing dispersion may be any one of the type commonly used in the art for natural rubber latex and contain filler, vulcanizer, accelerator, anti-oxidant, plasticizer, color, and other compounding ingredients. The only limitation is that such auxiliary materials do not cause coagulation of the latex when they are added. A typical vulcanizing dispersion which has been found satisfactory consists of:

Sodium salt of a sulfonated naphthalene-formaldehyde condensate 20 Water All the parts given are by weight.

Another example of a satisfactory vulcanizing dispersion suitable for natural rubber latex which was used 1n Examples 1-3 consists of:

Parts Zinc oxide 450 Sulfur Zinc dimethyldithiocarbamate 45 Sodium salt of a sulfonated naphthalene-formaldehyde condensate 45 Distilled water 945 The polyalkoxy-l-alkanols, either as the individual homolog or mixtures thereof, are lastly added to natural rubber latex, and compounded as previously described, generally in a concentration of 2 to 10%, but preferably 4 to 6%, so as to heat-sensitize the latex. Amounts lower than 2% will either fail to heat-sensitize the latex or else give unsatisfactory coagulates. Excessive additions of the polymethoxy alkanols serve no particularly useful purpose. 7

The following examples are given 'to illustrate the new and unexpected properties of the heat-sensitizers of the present invention and the eflicacy with which they cause rubber latex to deposit or coagulate rather thickfilms of rubber onto a hot form immersed in the latex,

EXAMPLE I Eight compositions with one control were prepared as shown in Table 1. It is to be noted that all components entering the nine compositions were weighed out in grams with the exception of the sulfuric acid which as noted is in milliliters.

Table l.-..-Use of mixed poIyalkoxy-I-alkanols as heatsensitizers for rubber latex Composition 1 2 3 Natural Rubber Latex 161. 7 161. 7 161. 7 161. 7 161. 7 161. 7 161. 7 161. 7 161.7 10% lz ilyoxyethylated Oleyl Alcohol D 0.995%]? Sulfuric Acid (1111s.).

p 40% Vnlcanizer ispersio 3:1 Polymethoxy Alcohols. :1 Polymethoxy Alcohols :1 Polymethoxy Alcohols :1 Polymethoxy Alcohols :1 Polymethoxy Alcohols. 5:1 Polyethoxy Alcohols 10:1 Polyethoxy Alcohols 15:1 Plyethoxy Alcohols p Coagulation Point "C After Preoaratio After 24 Hours at Room Temperature.

Flocc.

Floccu. ated 1 Centriiuged natural rubber latex; percent solids=61.85.

2 The reaction product of ethylene oxide and oleyl alcohol in the mole ratio of 20: 1.

I. APPEARANCE O13 LATEX After preparation:

1-6. Good; fluid; smooth. 7. Flocculated on continued stirring shortly after the 5:1 polyethoxy alcohols were added. 8-9. Good; fluid; smooth. After 24 hours at room temperature:

1-3. Good; fluid; smooth. 4. Flocculated even after shaking. 5. Flocculated until shaken then good, fluid, smooth. 6. Flocculated even after shaking. 7. Flocculated; coagulated on being shaken. 8-9. Flooeulated even after shaking.

II. APPEARANCE or ooaounsrn After preparation:

1-6. Good; fairly stro g; smooth coagulate; not too easily pulled apart by hand. 8-9. Good; fairly strong; smooth coagulate; not too easily pulled apart by hand. After 24 hours at room temperature:

1-3. Good; fairly strong; smooth coagulate; not too easily pulled apart by hand. 5. Good; fairly strong; smooth coagulate; not too easily pulled apart by hand.

The centrifuged natural rubber latex was weighed into a tared 400-1111. glass beaker following which 15 grams of the 10% solution of polyoxyethylated .oleyl alcohol Was added. The latex was then placed on a ring stand, and a stainless steel stirrer attached to a variable-speed motor was inserted into the latex. Stirring was then begun. The electrode leads of a Beckrnan pH meter were inserted into the latex and the motor turned on. Sulfuric acid (0.9954 N) was added .dropwise from a burette to a pH of 7.6. The vulcanizer dispersion was then added by diiference from a 3(l-rnl. beaker following which the polyalkoxy-l-alkanols were also added by diiference from a -1111. beaker. The pH of the latex was determined after each addition. The latex composition was stirred for several minutes after the polyalkoxy-l-alkanols were added and then poured into an 8-02. bottle, capped and labeled. The coagulation point was determined after 49 C. In one instance, the coagulation point of the heat-sensitized latex was apparently so low as to cause flocculation at room temperature. By comparison, a control sample prepared in exactly the same way but containing no polymethoxyor polyethoxy-l-alkanol had a coagulation point of 60" C. which is generally considered too high for a satisfactory heat-sensitized latex.

Dipping tests carried out on these compositions show that addition of 6% polymethoxyor polyethcxy-l-alkanols to a compounded rubber latex produces coagulates which are somewhat thicker and of better appearance than those obtained from a control containing no polyalkoxy-l-alkanols.

Dipping test-s AB E BAI CE 0 GOAGULAI Composition Appearance lee-Mo inch thick; thin, drippy, smooth coagulate. Seems to be little more than a thin skin on the tube.

lie-k; inch thick; thick, smooth, non-drippy coagulate.

Much better than 1.

Flocculated; not run. 7

V wk inch thick; thick, smooth, non-drippy coagulate.

' Much better than 1.

Flocculated; not run.

MODE OF PREPARATION A 20 x ISO-mm. Pyrex test tube was half-filled with glycerine and a thermometer inserted. The test tube and contents were heated over a gas flame to a temperature of C., immersed in the latex, which had been allowed to stand at room temperature for 24 hours, held for 30 seconds in the latex, and then withdrawn. Bottom temperature on withdrawing the test tube from the latex ranged from 79 to 82 C.

EXAMPLE II The compositions listed in Table 2 were prepared in the same manner as given in. Example I. However, in this case slightly more stabilizer was used to increase the coagulation point of the heat-sensitized latices. The latices were also stored for 24 hours in a refrigerator at 0-5 C. to prevent prematureooagulation of the latices. All parts are in grams unless otherwise noted.

sensitizers for rubber latex' Composition 1 2 3 4 5 6 7 8 9 Natural Rubber Latex 1151.7 161.7 161 7 161.7 161 7 161 7 161.7 161.7 161. 7 10% Polyoxyethelated Oleyl Alcohol 20 20 20 20 20 20 20 20 pH 10. 19 a 10. 19 10. l8 10. 16 10. 16 10. 18 10. 16 10. 17 10. 18 0.9954 N Sulfuric Acid (mls.)-. 59. 0 59. 4 69. 5 57. 2 59.3 59. 9 59. 8 60. 1 60. 2 pH 7. 63 7. 62 7. 64 7. 62 7. 62 7. 62 7. 63 7. 64 7. 65 40% Vulcanizer Dispersion 17. 5 17. 5 17.5 17. 5 17.5 17. 5 l7. 5 17. 5 17. 5 3:1 Polymethoxy Alcohols 6 5: 1 Polymethoxy Alcohols 6 1g: Polymethoxy Alcohols. 6 6

Polymethoxy Alcohols 6 6 Polyethoxy Alcohols- 6 pH 7. 72 7. 7a 7. 75 7. 73 7. 72 7.78 7:75; "7'56 7.76 Coagulation Point, C.: g I 7 After Preparation 60 53 52 43 42 45 35 52 53 After 24 Hours at (ll-5 0--.- 59 52 51 42 42 41 31 48 50 APPEARANCE 0 LATEX 20 The following dipping tests carried out on these com- Afier preparation. positions clearly illustrate the efliicacy with which the 1 Good. fluid. smooth various polyalkoxy-l-alkanols act to produce much thick- 2. Good; fluid; smooth.

3. Good; fluid; smooth.

4-6. Good; fluid; smooth.

7. Good; fairly thick; smooth.

8. Good; fluid; smooth.

9. Good; fluid; smooth.

After 24 hours at 0-5 9 C.:

1. Good; fluid; smooth.

2. Good; fluid; smooth.

3-5. Good; fluid; smooth.

6. Good; slightly thick; smooth.

7. Good; thick; smooth; almost flocculated on top at first until shaken then fluid; smooth.

- .8. Good; fluid; smooth.

9. Small amount of polyethoxy alcohols at top with small amount of latex almost flocculated; good, fluid, smooth when shaken.

APPEARANCE 0F COAGULATE.

After preparation:

1-9. Good, fairly strong, smooth coagulate; not too easily pulled apart by hand. After 24 hours at 0-5 C.: p

1-9. Good, fairly strong, smooth coagulate; not too easily pulled apart by hand.

The coagulation points of compounded rubber latex heat-sensitized by 6% additions of various polymethoxyor polyethoxy-l-alkanols (based on 100 parts of rubber latex solids) after preparation ranged from 35 to 53 C. as compared to 60 C. for the control." After standing for 24 hours at 0-5" 0., the coagulation point of compounded latices hea't-sensitized with: thevarious polyalkoxy-l-alkanols seemed to show a slight drop in some cases and ranged from 31 to 52 C. as compared to 59 C. for the control.

er, smoother, less drippycoagulates when used as heatsensitizers for natural 25 control.

Dipping tests APPEARANCE OF COAGULATES Composition Appearance 1 %2-%6 inch thick; thin, drippy, runny, fairly smooth coagulate. Little more than thin skin on tube.

2- Ms inchthick; fairlythickyslightly drippy, smooth,

even coagulate. Somewhat better than 1.

4-5 lie-9% inch thick; thick, .non-drippy, smooth, even coagulate. Much better than 1.

6 Almost 9t inch thick; thick, non-drippy, smooth, even coagulate. Very much better than 1.

7 %e% inch thick; thick, non-drippy, smooth, even coagulate. Much better than 1. (Note: The holding time was cut from 30 to 15 seconds because of the low coagulation point of this latex.)

8-9 Pie inch thick; fairly thick, smooth, even, drippy 4 coagulate. Somewhat better than 1.

MODE 0F PREPARATION v A 20x ISO-mm. Pyrex test tube' was half-filled with glycerine and a thermometer inserted. The test tube and 5 contents were heated over'a gas flame to a temperature of 90 C. immersed in the latex which had been stored in a refrigerator for 24 hours at 05 C. held for 30 seconds in the latex unless otherwise noted, and then withdrawn. .Bottom temperature on withdrawing the test tube from the latex ranged from 75-80 C. I

EXAMPLE III p The compositions listed'- -in-Table 3 were prepared in the same manner as given in Example II. The results obtained clearly show the improved results obtained when various individual members of different polyalkoxy-lalkanol series are used as heat-sensitizers for acompounded natural rubber latex; e

Table 3.-Use of individual polyalkoxy-I-alkanols as heat-sensitizers for rubber latex rubber latex as compared to a" Composition 1 2 3 34 5 p 6 7 8 Natural Rubber Latex 161. 7 161. 7 161. 7 161, 7 161. 7 161. 7 161. 7 161.7 10% Polyoxyethylatedflleyl Alcohol- 20 20 2O 20 20 20 s 20 20 pH 10. 40 10.46 V 10.51 10.55 10. 10.52 10. 62 10. 45 1.00l'N Sulfuric Acid (11715.) 60.0 60.4 60. 3 60.8 61. 1 61.0 60.8 61. 5 pH 7. 62 7. 63 7. 61 7. 62 7. 61 7. 61 7. 62 7. 63 40% Vulcanlzer Dispersion. 17. 5 17. 5 17. 5 17.5 17. 5 17.5 17. 5 17. 5 3,5,7-Trlmethoxy-1-octanol. 6 3,5,7,9,1l-Pentamethoxy-l-dodecanol. 6 3,5,7,9,11,13-Hexamethoxy-1-tetradecanol. 16 3,5,7,9-Tetraethoxy-1-decanol. I 7 3-Oetyloxy-1-butanoL 6 3,5,7,9 Tetra (2 methoxyethoxy) '1- decanol V 6 pH 7. 78 7. 79 7. 76 7. 79 7. 76 7. 48 7. 70 7. 48 Coagulation Point, C. After Preparation 60 56 53 53 52 47 57 47 After 24 Hours at 05 O 60 52 52 54 49 56 49 r APPEARANCE OF LATEX APPEARANCE OF COAGULATE After preparation:

l-8. Good; fairly strong coagulate; not easily pulled apart by hand. After 24 hours at -5 0.:

1-8. Good; fairly strong -coagulate;gnot easily pulled apart by hand.

Dipping. Tests APPEARANCE 0F COAGULATES Composition: 7 Appearance:

%2-M6 inch thick; thin, even, smooth, drippyr coague late. Little more thanthin skin on tube.

lie inch thick-y fairly thick, smooth, even, slightly drippy coagulate. Somewhat better than 1.

Pie-5e inchthick; thick, smooth, even, slightly drippy coagulate. Much better than 1.

He inch thick; fairly thick, smooth, even, drippy coa ate. Somewhat better than 1.

Mia-5 -inch-thick; thick, smooth, even, slightly drippy' coagulate. Somewhat better than 1.

MODE PREPARATION A 20 x' ISO-mm. Pyrex test tube was; half-filled with glycerine and a thermometer inserted. The. test tube and contents were heated over a gas flame to a temperature of 90 C., immersed in the latex which had been stored in a refrigerator for 24 hours at 0-5" G, held for 30 seconds in the latex, and then withdrawn. Bottom temperature on withdrawing the test tube from the latex ranged from 757 8 C.

From the foregoing tables. it is clearly apparentthat the individual and mixed polyalkoxy-l-alkanols can be readily. employed to heat-sensitize natural rubber latex for the production of dipped goods, impregnation of paper, preparation. of sponge rubber, etc.

I; A rubber latex composition adaptablev for the manufacture of'rubber articles by coagulationata temperature between 30-l30 C.,, containingv in a heat-sensitizing amount at least one polyalkoxy-l-alkanol characterized by the following general formulawhere R and R represent a member selected from the class consisting of alkyl of l to 4 carbon atoms and alkoxyalkyl groups of 3 to 7 carbon atoms, R" represents a member selected from the class consisting ofhydrogen, alkyl of 1 to 4 carbon atoms and alkoxyalkyl groups of. 3

to 7' carbon atoms, and n represents a positive integer of l to 40. a

2. A rubber latex; composition according to claim 1 formula a ong-on I cur-omen 3. A rubber latex: composition according to claim 1 12 wherein the polyalleoxy-lallianolhas the following formula I I H GH1C- H C .2CH2QH 4. A rubber latex composition. according to claim 1 wherein thepolyalkoxy-l-alkanol has the following formula E em-c iff 1 crnomon L OCHiJa 5. A rubber latex composition according to claim '1 wherein the polyalkoxy-l-alkanol has thefollowing for mula 6. A rubber latex composition according to claim 1' wherein the polyalkoxy-l alkanol has the following formula HC nrorhlo-Hromon 0 3119 V 9. A process according to claim 7 wliereinthe polyalkoxy-l-alkanol has the following formula H QCHsJio 10. A process: according to: claim 7 wherein. the polyalkoxy-l-alkanol has the following formula H GHrOH. 1 CHaQHhOE.

L teal.

11. A process according to claim 7 wherein the polyalkoxy-l-alkanol has the following formula L all.

l2. A process according to claim 7 wherein the polyj 'alkoxy-l-alkanol has therfollowing formula L. 0 OKs-I19 

1. A RUBBER LATEX COMPOSITION ADAPTABLE FOR THE MANUFACTURE OF RUBBER ARTICLES BY COAGULATION AT A TEMPERATURE BETWEEN 30*-130*C., CONTAINING IN A HEAT-SENSITIZING AMOUNT AT LEAST ONE POLYALKOXY-ALKAANOL CHARACTERIZED BY THE FOLLOWING GENERAL FORMULA 